Many telecommunications network services providers, cable TV operators, and telecommunications equipment providers are showing significant interest in provisioning content distribution services such as Video-on-Demand (VOD). Primary application areas include on-demand home entertainment, remote learning and training, video conferencing, and news-on-demand. These services are expected to grow significantly over time and become an important source of income for the service providers. However, in order to provide adequate service, significant bandwidth resources must be available, which implies large capital investments. For example, in near-VOD applications a server may broadcast a copy of a popular movie every five minutes, which implies that a customer may wait, on average, 2.5 minutes. Thus, if the length of the movie is 100 minutes, the network would carry simultaneously 20 copies of the movie, which would require significant bandwidth resources.
Numerous papers discuss content distribution delivery technologies that are expected to be practical for large-scale problems. These include the papers by B. Li and J. Liu, “Multirate Video Multicast Over the Internet: An Overview”, IEEE Network, 17, 24-29, January/February 2003, and by K. A. Hua, M. A. Tantaoui, and W. Tavanapong, “Video Delivery Technologies for Large-Scale Deployment of Multimedia Applications”, Proceedings of the IEEE, 92, 1439-1451, September 2004. Nevertheless, even with effective delivery technologies, the bandwidth requirements would be large, and an effective method of allocating the available bandwidth resources is needed.
A service provider may install servers at strategic nodes of the network and assign various program families at each of these servers. A program family is an aggregation of similar programs; for example, children's movies may be represented by one family. The term “program” will be understood to include program families. Each server broadcasts (more precisely, multicasts) its programs on a tree network. Trees associated with different servers may have joint links. Each link in the network has limited bandwidth capacity, and each node in the network has demand for a subset of the programs. The objective is to allocate the available bandwidth on all the links among the programs carried on these links in an optimal way that provides equitable service to all requested programs at all nodes. The service provided to any of the nodes requesting a specific program is specified through a performance function that represents satisfaction from the quality provided which, in turn, depends on the allocated bandwidth. The problem of finding an equitable bandwidth allocation is formulated as a lexicographic maximin optimization problem.
Current state-of-the-art systems use ad-hoc heuristics and communications network managers' experience for VOD bandwidth allocation. Some optimization-based methods for the simultaneous optimal allocation of bandwidth on all links of the content distribution network have been published. C. Y. Lee, Y. P. Moon, and Y. J. Cho, “A Lexicographically Fair Allocation of Discrete Bandwidth for Multirate Multicast Traffics”, Computers and Operations Research, 31, 2349-2363, 2004 and C. Y. Lee and H. K. Cho, “Discrete Bandwidth Allocation Considering Fairness and Transmission load in Multicast Networks”, Computers and Operations Research, 34, 884-899, 2007 present related models that approximate an equitable service objective through the minimization of the sum of convex decreasing functions and use heuristic methods, specifically, tabu search and genetic algorithm heuristics, to solve the model with the approximate objective. H. Luss, “Bandwidth Allocation for Video-on-Demand Networks”, U.S. patent application Ser. No. 11/268,105, filed on Nov. 7, 2005 (hereafter referred to as the '105 application) provides an optimization algorithm to the lexicographic maximin optimization problem; however, the method uses a bisection search which implies that the required computational effort is not polynomial as it depends on a specified desired accuracy parameter. The method is also described in the paper by H. Luss, “An Equitable Bandwidth Allocation Model for Video-on-Demand Networks”, Networks and Spatial Economics, 8, 23-41, 2008. The current invention provides a new method for finding the equitable solution where the computational effort of the new method is polynomial for wide classes of performance functions.